title: Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis.
abstract: OBJECTIVE
  To evaluate the ability of parameters measured by three-dimensional (3D) corneal and anterior segment optical coherence tomography (CAS-OCT) and a rotating Scheimpflug camera combined with a Placido topography system (Scheimpflug camera with topography) to discriminate between normal eyes and forme fruste keratoconus.
  
  
  METHODS
  Forty-eight eyes of 48 patients with keratoconus, 25 eyes of 25 patients with forme fruste keratoconus and 128 eyes of 128 normal subjects were evaluated. Anterior and posterior keratometric parameters (steep K, flat K, average K), elevation, topographic parameters, regular and irregular astigmatism (spherical, asymmetry, regular and higher-order astigmatism) and five pachymetric parameters (minimum, minimum-median, inferior-superior, inferotemporal-superonasal, vertical thinnest location of the cornea) were measured using 3D CAS-OCT and a Scheimpflug camera with topography. The area under the receiver operating curve (AUROC) was calculated to assess the discrimination ability. Compatibility and repeatability of both devices were evaluated.
  
  
  RESULTS
  Posterior surface elevation showed higher AUROC values in discrimination analysis of forme fruste keratoconus using both devices. Both instruments showed significant linear correlations (p<0.05, Pearson's correlation coefficient) and good repeatability (ICCs: 0.885-0.999) for normal and forme fruste keratoconus.
  
  
  CONCLUSIONS
  Posterior elevation was the best discrimination parameter for forme fruste keratoconus. Both instruments presented good correlation and repeatability for this condition.
authors.affiliation: Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, , Tsukuba, Ibaraki, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Fukuda
authors.forename: Simone
authors.initials: S
authors.lastname: Beheregaray
authors.forename: Sujin
authors.initials: S
authors.lastname: Hoshi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamanari
authors.forename: Yiheng
authors.initials: Y
authors.lastname: Lim
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hiraoka
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yasuno
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Oshika
mesh_terms: D000328:Adult; D019781:Corneal Topography / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D007640:Keratoconus / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010781:Photography / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D055815:Young Adult
keywords: forme fruste keratoconus; receiver operating characteristic curve; rotating scheimpflug camera with placido topography system; three dimensional anterior segment optical coherence tomography